Question: Simplify the following expression: $y = \dfrac{6}{5n} - \dfrac{1}{7n}$
Solution: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $5n$ and $7n$ $\lcm(5n, 7n) = 35n$ $ y = \dfrac{7}{7} \cdot \dfrac{6}{5n} - \dfrac{5}{5} \cdot \dfrac{1}{7n} $ $y = \dfrac{42}{35n} - \dfrac{5}{35n}$ $y = \dfrac{42 -5}{35n}$ $y = \dfrac{37}{35n}$